We are extending our studies in the whole animal on the action of ionizing radiation on nucleic acid metabolism in tissue. To minimize the physiological perturbations which are operative in such experiments and to enable us to better interpret such data, we have enlarged our program to include tissue culture experiments. It is hoped that such studies will lead to a better understanding for how radiation interferes with cell function and results in cell death. BIBLIOGRAPHIC REFERENCE: Effects of X-radiation on Liver RNA Metabolism in Specifically-Shielded Rats. Abdel-Halim, M., and Yatvin, M.B., Radiation Research, March, l976.